1. Field of the Invention
The present invention relates to a synchronous motor that employs magnets.
2. Description of the Related Art
Synchronous motors in the form of linear or rotary direct drive mechanisms play an increasingly important role in technology. Such direct drive mechanisms do not require any mechanical transmissions, they themselves move the useful load.
An example of such a direct drive mechanism is described in EP 0 793 870 B1. A stator supports teeth wound with coils, a rotor supports evenly arranged permanent magnets. These magnets are customarily glued onto a magnetic flux conductor. For certain applications, for example in connection with a turntable of a machine tool, very high numbers of revolutions are demanded of such a direct drive. Because of centrifugal forces, it is possible that the adherence of such a magnet to its substrate becomes detached at high numbers of revolutions. Waste heat occurring at high numbers of revolutions heats the motor excessively and in this way further contributes to the fact that it is no longer sufficient to glue the magnets on when encountering high numbers of revolutions.
Eddy currents are also responsible for heating the motor. Therefore the coils of the stator are wound on a laminated core, whose individual laminations are insulated against each other. The flux conductor of the rotor is occasionally designed in the form of a laminated core. For stopping eddy currents in the magnets themselves, JP04079741A has already proposed segmented magnets for motors, which are put together from several layers or segments which are insulated against each other. However, at high numbers of revolutions these steps alone do no result in a sufficiently stable connection between the magnet and rotor.
It has also already been proposed to clamp the magnets in addition to gluing. DE 100 53 694 A1 describes such a synchronous motor. Clamping of the magnets in place is achieved by clamping elements alt ached to the front of the rotor, which initially have individual clamping claws, and clamping the magnets in place on the rotor is achieved by bending the clamping claws in an axial orientation. However, additional components are required for this solution, moreover, the magnets are only clamped in place at the ends of the rotor.